1. Technical Field
The present invention relates to a semiconductor memory system, and more particularly, to a secure boot method and a semiconductor memory system using the method.
2. Discussion of the Related Art
Many electronic apparatuses perform a boot process to ensure normal operation. During the boot process, the electronic apparatus is appropriately initialized and loads a program to a main memory. The boot process determines the initial state of the electronic apparatus and affects major operational parameters. Also, the boot process may substantially affect how the electronic apparatus functions. Because of the significance of the boot process, it may be desirable to prevent users from tampering with the boot process to ensure that the electronic apparatus functions normally and in an intended manner. Moreover, many electronic apparatuses execute software in a secure environment and thus it is desirable to protect the boot process from modification so as to maintain the security of the environment.
For example, makers of high priced home game consoles may sell hardware itself at a low price and pursue profit through the sales of software. The hardware may then authenticate the software prior to execution to prevent the execution of unauthorized copies of software and/or arbitrary code. If a user is able to easily change the boot process to execute unauthorized copies of software and/or arbitrary code in the game console, the makers may loose profits.
Accordingly, makers selling electronic apparatuses desire a secure boot method that is versatile enough to execute a desired boot process and yet cannot be easily changed.
Also, manufacturers of electronic apparatuses or service providers using the electronic apparatuses may desire to keep a secret key safe in the electronic apparatus. The secret key can be used for a variety of purposes. For example, the secret key can be used to encrypt, at least in part, a kernel or establish a secure communication channel between the electronic apparatus and the manufacturers or service providers. In order to keep the secret key safe, a secure storage space is generally provided inside the electronic apparatus. A one-time programmable (OTP) memory in a system on chip (SoC) has been used to keep the secret key safe within electronic apparatuses.
The OTP memory can be used to keep the secret key safe when the secure boot method is used. Generally, the cell size of the OTP memory is larger than that of common memory. Thus, use of OTP memory may cause an increase in manufacturing costs. Also, because the OTP memory may take longer to record to than conventional memory, manufacturing of electronic apparatus utilizing OTP memory may take longer than for conventional devices and thus fewer units of the electronic apparatus may be produced in a given period of time.